Typically, an electronic device refers to a device which performs a specific function corresponding to an installed program, such as a home appliance, an electronic diary, a portable multimedia player, a mobile communication terminal, a tablet PC, an image/sound unit, a desktop/laptop computer, a navigation unit for a vehicle, and the like. For example, such an electronic device can output stored information in the form of sound or image. With the increase of degree of integration and the popularization of hyper-speed and high capacity wireless communication, recently, a single mobile communication terminal has various functions. For example, an entertainment function such as a game, a multimedia function such as reproduction of a music file and a video file, a communication and security function for mobile banking or the like, a scheduling function, an electronic wallet function, etc. are integrated into a single electronic device, in addition to a communication function.
A portable electronic device, such as an electronic diary, a portable multimedia player, a mobile communication terminal, or a tablet PC, is generally equipped with a flat display device and a battery and has the appearance of a bar type, a folder type, or a sliding type. Recent developments in electronic communication technology has made such electronic device more compact and even commercialized electronic devices that can be worn on a part of the human body, such as the wrist or the head.